Field of the Invention
The present invention relates to a method for controlling a wireless feeder network used to couple access base stations of an access network with a communications network and to various components within such a wireless feeder network.
Description of the Prior Art
Various types of access network which provide a wireless link between end user equipment and a communications network are known, for example using standards such as WiFi, WiMAX, or LTE. The wireless links are formed between the end user equipment and access base stations which provide the connection between the access network and the communications network.
Whilst the access base stations could be coupled to the communications network via fixed, wired connections (a wired “backhaul” connection) it is known that a greater degree of flexibility with regard to the placement and configuration of the access base stations is possible if the connection between the access base stations and the communications network is provided by a dedicated wireless backhaul connection. Yet although such a wireless backhaul solution may provide a connection which is more easily deployed, it instead faces significant challenges with regard to the appropriate use of the scarce radio frequencies which must be allocated in advance to the wireless backhaul connection (as opposed to the frequencies allocated for the access network).
Due to the scarcity of the radio frequencies available for providing this wireless backhaul connection, various techniques have been developed to improve the throughput of such a connection. For example, techniques such as Automatic Repeat Request (ARQ), Hybrid ARQ (HARQ), HARQ with soft combining and so on have been developed to improve the reliability with which data may be transmitted via such a connection. However, although such techniques generally can provide a significant improvement in the data throughput by means of their error detection and correction capabilities, these techniques require a re-transmission of data via the wireless connection if the error correction/detection provided is insufficient to decode that data. Such a retransmission must be scheduled amongst the ongoing data being transmitted via the wireless connection, and will require its own handshake protocols to ensure positive reception of the retransmitted PDU (protocol data unit), all resulting in additional undesirable latency.
An alternative approach to improving the data reception rate of a receiver is given by beam-forming techniques according to which closely located wireless receivers are provided with a wired connection allowing a weighted antenna beam shape to be generated and to improve the wireless throughput of an individual antenna by means of additional contributions from the neighbouring antenna to which it is coupled. However, such beam-forming techniques generally require a large bandwidth wired connection to be provided between the antenna and lack flexibility in the context of a generic wireless connection to be provided between access base stations and a communications network such that it is easily deployed and reconfigured.
Accordingly, it would be desirable to provide an improved technique for coupling access base stations of an access network with a communications network, which allows freedom in the placement of base stations of the access network, whilst improving the wireless throughput and avoiding the above mentioned prior art drawbacks.